Yong Hoon Park

Atypical hemolytic uremic syndrome: Korean pediatric series.

Atypical hemolytic uremic syndrome (aHUS) is a rare disease with a genetic predisposition. Few studies have evaluated the disease in the Asian population. We studied a Korean pediatric cohort to delineate the clinical characteristics and genotypes.

A Nationwide Epidemiological Study of Nocturnal Enuresis in Korean Adolescents and Adults: Population Based Cross Sectional Study

We performed a nationwide epidemiological study to evaluate the prevalence and characteristics of nocturnal enuresis (NE) in Korean adolescents and adults. A questionnaire was sent via e-mail to 51,073 people aged 16-40 yr by stratified sampling according to age, sex, and region among a 200,000 internet survey panel pool. The questionnaire included following information; presence or absence of NE, frequency of NE, possible risk factors for NE, self-esteem scale score and depression score results, and measures for the treatment of NE. Among the 2,117 responders, 54 (2.6%) had NE (≥1 enuretic episode within 6 months). Of 54 bedwetters, 9.3% wet ≥1 night per week and 20.5% wet ≥1 per month. The prevalence rates remained relatively stable with no apparent trend of reduction with age. The presence of sleep disturbance, family history, urgency, or urge incontinence increased the probability of NE episode significantly. The self-esteem score was lower (P=0.053) and the depression scale score was higher (P=0.003) in bedwetters compared with non-bedwetters. Overall 2.6% of Korean aged 16-40 yr have NE. The higher rate of urgency and urge incontinence in adolescent and adult enuretics suggests that bladder function has an important role in adolescent and adult NE.

Long-term renal outcome in children with OCRL mutations: retrospective analysis of a large international cohort

Background Lowe syndrome (LS) and Dent-2 disease (DD2) are disorders associated with mutations in the OCRL gene and characterized by progressive chronic kidney disease (CKD). Here, we aimed to investigate the long-term renal outcome and identify potential determinants of CKD and its progression in children with these tubulopathies. Methods Retrospective analyses were conducted of clinical and genetic data in a cohort of 106 boys (LS: 88 and DD2: 18). For genotype-phenotype analysis, we grouped mutations according to their type and localization. To investigate progression of CKD we used survival analysis by Kaplan-Meier method using stage 3 CKD as the end-point. Results Median estimated glomerular filtration rate (eGFR) was lower in the LS group compared with DD2 (58.8 versus 87.4 mL/min/1.73 m2, P < 0.01). CKD stage II-V was found in 82% of patients, of these 58% and 28% had moderate-to-severe CKD in LS and DD2, respectively. Three patients (3%), all with LS, developed stage 5 of CKD. Survival analysis showed that LS was also associated with a faster CKD progression than DD2 (P < 0.01). On multivariate analysis, eGFR was dependent only on age (b = -0.46, P < 0.001). Localization, but not type of mutations, tended to correlate with eGFR. There was also no significant association between presence of nephrocalcinosis, hypercalciuria, proteinuria and number of adverse clinical events and CKD. Conclusions CKD is commonly found in children with OCRL mutations. CKD progression was strongly related to the underlying diagnosis but did not associate with clinical parameters, such as nephrocalcinosis or proteinuria.

Dense deposit disease in Korean children: a multicenter clinicopathologic study.

The purpose of this study was to investigate the clinical, laboratory, and pathologic characteristics of dense deposit disease (DDD) in Korean children and to determine whether these characteristics differ between Korean and American children with DDD. In 2010, we sent a structured protocol about DDD to pediatric nephrologists throughout Korea. The data collected were compared with previously published data on 14 American children with DDD. Korean children had lower 24-hr urine protein excretion and higher serum albumin levels than American children. The light microscopic findings revealed that a higher percentage of Korean children had membranoproliferative glomerulonephritis patterns (Korean, 77.8%; American, 28.6%, P = 0.036), whereas a higher percentage of American children had crescents (Korean, 0%; American, 78.6%, P < 0.001). The findings from the electron microscopy revealed that Korean children were more likely to have segmental electron dense deposits in the lamina densa of the glomerular basement membrane (Korean, 100%; American, 28.6%, P = 0.002); mesangial deposit was more frequent in American children (Korean, 66.7%; American, 100%, P = 0.047). The histological findings revealed that Korean children with DDD were more likely to show membranoproliferative glomerulonephritis patterns than American children. The degree of proteinuria and hypoalbuminemia was milder in Korean children than American children.